While the registration apparatus of the present invention has applications beyond the handling of a web in a pouch form, fill, seal machine, the invention will be described in relation to such a pouch form, fill, seal machine in order to illustrate the registration problems of that machine prior to the present invention and to illustrate the manner in which the present invention solves those problems. A typical form, fill, seal machine is illustrated in Cloud U.S. Pat. No. 3,597,898. The machine includes a supply roll containing an elongated web. The web is fed through drive rolls which are positively driven and whose speed is variable, as will be described, in order to maintain proper registration of the web. The web has printed matter on its surface and has registration marks between each set of printed matter, the registration marks being placed generally in the area where transverse seals are to be formed in order to form the pouches. The web is passed over a plow which forms a longitudinal fold in the web. Thereafter, the web is passed around a sealer rotatable about a vertical axis and having a plurality of vertical heated lands in order to form transverse seals in the web. The web is retained in engagement with a land for more than 180.degree. of the revolution of the sealer, during which excursion the land forms a seal in the web. It is important that the registration mark, or more particularly, the space between the printed matter on the pouch, be properly aligned with the land so that the seal will be formed precisely centered between the printed matter of adjacent pouches. It was the function of prior registration apparatus, and it is the function of the present invention to maintain such an alignment.
After the vertical seals are formed, the web is fed into a rotary filler where product is poured into the respective pouches and thereafter a top longitudinal seal is formed and the pouches are individually cut from the web.
The prior registration apparatus includes a V-belt drive for the drive rolls, the V-belt passing over a pulley having a variable circumference. An idler roller, driven by an air cylinder, is employed to vary the tension in the V-belt. When the tension is increased, the V-belt runs deeper in the variable circumference pulley and hence the pulley runs faster. Conversely, when tension on the idler is reduced, the V-belt rides out of the variable circumference pulley and the drive is slower.
The air cylinder is provided with stops so as to limit the amount of correction that is imparted. A photoelectric scanner is provided to determine the position of the registration marks. A rotatable disk, driven by the machine, is provided with a hole and an electric eye which cooperates to determine the position of the lands on the vertical sealer.
In normal operation, with the registration mark slightly ahead of the vertical sealer lands and the air cylinder de-activated, the web is driven slightly slower than required for proper engagement with the vertical sealer. In this condition the pulses from the registration marks occur slightly ahead of the pulses from the vertical sealer. As the machine runs, the pulses corresponding to the registration marks occur gradually closer to the pulses from the vertical sealer, as the web drops back due to the slightly slow feed rate. When the pulses coincide, the air cylinder is activated to cause the web drive to increase in speed slightly above the required for proper engagement with the vertical sealer. When the pulses do not coincide, the air cylinder is de-activated and the web, being driven slightly slower than the sealer, again drifts backward until coincidence once again is realized.
Provision is made for two corrections by the machine operator. The first correction, made by manipulating knobs on the machine, turns a screw driving the air cylinder in one direction or the other to substantially increase or decrease the drive of the web. This adjustment could be made while the machine is running. The other adjustment, made when the machine is shut down, is to adjust the stops on the air cylinder so as to vary the incremental change imparted by the activation of the air cylinder.
This registration system as described above has had several disadvantages whose ultimate result was the production of scrap and machine down time which reduced the product being packaged on the machine in a given period of time.
Among the disadvantages is the fact that the system requires frequent adjustment on the part of the operator which is reasonably satisfactory if the operator is skilled, but if not, much scrap and down time results. The V-belt system is too crude and lacking in precision. The V-belt itself is spliced, and that has a tendency to make it run irregularly. Further, where a splice occurs in the web, thus putting the registration marks immediately out of alignment, too many pouches have to be run in order to bring the system back into alignment. This latter disadvantage arises in part out of the fact that the correction is uni-directional and active over only a small portion of the cycle. Therefore, a mark placed out of the active range must drift slowly backwards until it returns to the "in-register" position.
Finally, there is a limitation on the amount of correction, the limitation being imposed by the stops on the air cylinder.